The invention relates to an opening roller for an open-end spinning device with numerous combing teeth designed for combing out fibers out of a sliver, and which are arranged in numerous windings or ring-formed rows extending in circumferential direction of the opening roller, with at least a part of the helixes or ring-formed rows comprising zones with reduced combing effect or entirely without combing-out effect.
Usually opening rollers are provided with a fitting of combing teeth or combing needles in order to comb out fibers, which are to be spun into a yarn, from a fed-in sliver. The combing teeth are normally arranged on the opening roller in rows or helixes, extending in circumferential direction of the opening roller and with spaces between them, the spaces forming grooves.
On an opening roller to be used for the production of an even yarn, the combing teeth are uniformly made and arranged in rows or helixes equidistant from each other. Due to their contour, the combing teeth are suitable for combing out individual fibers from a fed-in sliver as soon as the fibers are released from the nipping line of the sliver feeding device. The combed-out fibers mainly reach the grooves formed by the rows or windings of the combing teeth and are taken along by the rotating opening roller to a fiber feed channel. Due to the prevailing under pressure there and to the effect of the centrifugal forces exerted by the opening roller, the fibers are released from the fitting and reach the fiber feed channel.
In order to generate the necessary centrifugal forces for the releasing of the fibers, the opening roller must rotate at a high number of revolutions. The fibers held at the nipping line are subject to numerous strokes from the combing teeth of the opening roller, the opening roller rotating at high speed, before they are released from the nipping line and combed out of the fiber beard by the combing teeth. The high number of strokes from the combing teeth lead frequently to mechanical damage of the fibers.
An opening roller having at least one discontinuity is known from the German patent application 40 24 786 A1. The discontinuity can consist in a zone without combing-out effect being provided in a row of combing teeth, or in a groove filled with an insert which thereby partly reduces the transport function of the opening roller.
The discontinuity is arranged on the fitting in such a way that, during the spinning process, varying amounts of fibers are fed into the fiber feed channel in order to be able to produce an uneven yarn.
An object of the invention is to manufacture an opening roller with which the mechanical stress of the fibers is reduced without giving rise to an uneven yarn.
This object is achieved in that the zones with reduced or entirely without combing-out effect are so designed and arranged relative to the combing teeth that the fibers are combed out of the sliver evenly.
The arrangement of zones with reduced or entirely without combing-out effect in place of combing teeth results in the number of strokes carried out on the fibers until their release from the nipping line being reduced. The number of combing teeth can be reduced by such an amount, and replaced by zones with reduced or entirely without combing-out effect, that the combing-out effect needed for the release of the necessary amount of fibers for spinning is just sufficient.
The design and arrangement of the zones with reduced or entirely without combing-out effect results in the more careful treatment of the fibers during combing-out from the sliver not having an effect on the evenness of the yarn. The spinning element can be continuously fed with a mainly constant amount of fibers. The grooves are maintained, so that the transport of the released fibers is not disturbed.
In an advantageous development, the zones with reduced or entirely without combing-out effect are arranged distributed over the axial width of the opening roller. A good evenness is hereby maintained during fiber release.
It is further advantageous to distribute the zones with reduced or entirely without combing-out effect evenly over the opening roller, namely over its axial width and/or in circumferential direction.
In an advantageous development, a zone with reduced or entirely without combing-out effect is so designed that it comprises at least one so-called "modified tooth", (whose function differs from that of a normal combing tooth), projecting from the opening roller. The modified tooth is so designed that it can transport fibers but has no, or only a reduced, combing-out effect. The modified teeth, projecting from the opening roller in place of the combing teeth, enable a careful treatment of the fibers during the combing-out process, and also the forming of grooves, which ensure an even transport of the released fibers.
In an advantageous development, the modified tooth projecting from the opening roller has the contour of a tooth whose face angle is smaller than that of a combing tooth. Due to the smaller face angle, a combing-out effect of the tooth is avoided or at least reduced.
In an advantageous development, a zone with reduced or entirely without combing-out effect is formed on the extended back of a combing tooth or a tooth with a smaller face angle. The tooth tip and the tooth face of the combing tooth form a zone with combing-out effect, while the area of the extended tooth back forms a projecting modified tooth, which is then part of a zone with reduced or entirely without combing-out effect.
In an advantageous development, the combing teeth and the radially projecting modified teeth together form a continuous wall in circumferential direction of the opening roller, whereby in the area of the zones with reduced or entirely without combing-out effect, the contour of the combing teeth and the contours of the invention are formed into the continuous wall.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.